================
@@ -20,17 +21,117 @@ using namespace cir;
// Helpers
//===----------------------------------------------------------------------===//
+static constexpr unsigned MaxLookupDepth = 6;
+
mlir::Value CIRBasicAliasAnalysis::getUnderlyingObject(mlir::Value val) {
LDBG() << "Getting underlying object for: " << val;
- // TODO: Walk through cir.ptr_stride, cir.cast, cir.get_member, etc.
- // to find the root allocation (cir.alloca, cir.global_addr, function args).
- LDBG() << "Not yet implemented";
+ for (unsigned depth = 0; depth < MaxLookupDepth; ++depth) {
+ mlir::Operation *defOp = val.getDefiningOp();
+ if (!defOp) {
+ LDBG() << "No defining operation, stopping";
+ break; // Block argument (e.g. function parameter) — stop here.
+ }
+
+ // Bitcast and address-space casts don't change the underlying object.
+ // array_to_ptrdecay produces an element pointer to the same storage as
+ // the array pointer, so strip through it too.
+ if (auto castOp = mlir::dyn_cast<cir::CastOp>(defOp)) {
----------------
andykaylor wrote:
I ended up needing to generalize this quite a bit to get the partial alias
handling to work, so a lot of what I have here will be replaced. My plan is to
have a follow-up PR that does the reorganization and calculates the offset, but
still only handles the `MustAlias` cases so the tests will remain the same. I
had already posted this for review before I came to that conclusion though, and
I think this version is easier to follow for review purposes. I can just tack
that commit onto this PR if you'd prefer. It's going to look like a substantial
replacement of this one either way. So, whatever is easier for review is fine
with me.
https://github.com/llvm/llvm-project/pull/215683
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